Recently I tried to upgrade my Mac from Catalina to Big Sur. I have done OS upgrades in the past without any problems. I assumed it would be the same with Big Sur. I was wrong.
I am not sure if the problem was with Big Sur or the state of my Mac. I do know my MacBook Air was down to less than 20 GB free. When I tried to install Big Sur, my Mac first started complaining about that. However after I freed up more space (just above 20 GB) it proceeded with the install.
While it proceeded, it did not complete. No matter what I did, I could not get it to boot all the way up. Recovery mode did not resolve the problem. Internet recovery mode would allow me to install Mac OS Mojave, but not Catalina or Big Sur.
Initially I tried installing Mojave, but after the install was complete, I got a circle with a line through it (not a good sign). I tried resetting NVRAM or PRAM and that helped me get further, but even as I logged in, I could not get the MacOS to fully boot up (it just went back to the login).
Eventually I did the following:
- Bought a 256 GB flash drive. Mine was from Kingston. I bought a size that matched my drive. I could have gotten away with a smaller one, but I was tired and didn’t want to risk not having enough space to use it as a backup.
- Put the flash drive into the Mac (I had a dongle to connect regular USB to USB-C)
- Booted up the mac by going into Internet recovery mode
- Went into disk utilities and made sure my Macintosh HD, Macintosh HD – Data and KINGSTON drive were mounted. (I used the MOUNT button to mount them if they weren’t mounted).
- Ran FIRST AID on all disks.
- Left Disk Utility. Clicked on Utilities > Terminal
- Copied my most important files from Macintosh HD – DATA to KINGSTON (both of them could be found in the directory /Volumes. For example, /Volumes/KINGSTON.) The files I wanted to backup were in /Volumes/Macintosh*DATA/Users/bernie/Documents (I think).
- Once I copied the files onto the USB Drive — it took hours — I checked to make sure they were there. I then got rid of a lot more files from the Documents area on my hard drive. After careful deleting, I had about 50 GB free. At one point I was talking to AppleCare and the support person said: yeah, you need a lot more than 20 GB of free space. So I made a lot.
- Then I went back into Disk Utility and erased Macintosh HD
- This is important: I DID NOT ERASE Macintosh HD – DATA! Note: before you erase any drive using the Disk Utility, pursue other options, like contacting AppleCare. I did not erase Macintosh HD – DATA in order to save time later on recovering files. I was only going to erase it as a very last resort. It turns out I was ok with not erasing it. The problem were all on the Macintosh HD volume, the volume I DID erase.)
- Once I did that, I shut down and then came up in Internet Recovery Mode again. THIS TIME, I had the option of installing Big Sur (not Mojave). I installed Big Sur. It created a new userid for me: it didn’t recognize my old one.
- I was able to login this time and get the typical desk top. So that was all good.
- Now here is the interesting part: my computer now had two Macintosh HD – Data drives: an old one and a new one. What I did was shutdown and go into Internet Recovery Mode again and mounted both drives. I also mounted the KINGSTON USB drive. Then I moved files from the old Macintosh HD – Data to the new one. (You can use the mv command in Terminal. I did, plus I also did cp -R for recursive copying).
- My Mac is now recovered. Kinda. I mean, there are all sort of browser stuff that needed to be recovered. I had to reinstall all my favorite apps. Etc. But it is a working MacBook.
All in all, I learned a ton when it comes to recovering a Mac. If you are reading this because your Mac is in a similar situation, I wish you success.
While I was trying to do the repair, these links were helpful:
- If your Mac starts up to a circle with a line through it – Apple Support
- Use macOS Recovery on an Intel-based Mac – Apple Support
- Command R Not Working! How To Reinstall macOS If Recovery Won’t Work – Macworld UK
- Stuck in a macOS update loop because there is not enough free space
- Not enough free space on your disk to ins… – Apple Community
- If your Mac doesn’t start up all the way – Apple Support
- About macOS Recovery on Intel-based Mac computers – Apple Support
- How to access a non-bootable Macintosh hard drive for file recovery | Information Technology Services
- Troubleshoot Your Mac With These Hidden Startup Options
- Reset NVRAM or PRAM on your Mac – Apple Support
- My MacBook can’t find startup disk after … – Apple Community